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Small Dispacement Nitro/methanol NA 2S engine questions

Small Dispacement Nitro/methanol NA 2S engine questions

Small Dispacement Nitro/methanol NA 2S engine questions

(OP)
Greetings!

I build/race model airplanes.  My latest project is to attempt to bump up the power delivery and RPM of an engine I'm using in a particular airframe.

It's called a Moki 210.  2.10cid (34.4cc) with a 36mmbx34mms.

These engines come from Europe where nitromethane is next to impossible to get.  That being said they are designed/intended to run on a blend of methanol and bean/castor oil.  Here in the states we can buy nitro but due to the compression ratio only about 10% will work with the stock CR.

I own a full service CNC machine shop.  I am making a new crank (stock ones don't last much past 10K rpm) new rod, and a piston using no rings.  I plan on running a tapered bore with a choke near TDC that'll open up once the engine warms up to operating temp.

I'd like help with configuring a good CR for a 50% nitro/50% methanol blend.  I'm guessing around 8:1-9:1.

The end goal is to spin a 16" X 16" pitch prop at 15,000rpm.  Right now the engine will run it at 7400.  At 15K this gives me a round about speed potential of 225mph.  That's ignoring things like drag.  I'm guessing 170-180 is more likely.  Plenty fast for this airframe. (terrifying fast for this plane actually)

Thoughts, comments, suggestions, and help is much appreciated!

C

RE: Small Dispacement Nitro/methanol NA 2S engine questions

(OP)
More info.  The engine uses a glow plug for ignition.  It's a platinum coil that reacts with the methanol in the fuel.  Heat is the catalyst.  Varying the platinum percentage alters the timing like on a distributor.

 

RE: Small Dispacement Nitro/methanol NA 2S engine questions

What prop material?

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Small Dispacement Nitro/methanol NA 2S engine questions

>"I'd like help with configuring a good CR for a 50% nitro/50% methanol blend."<

Good luck, you're going to need it.  BTW, nitro is widely available in Europe, it just costs a lot.  50% pop is what Fox Blast was, and a lot of guys ruined a lot of engines with it.

A 50/50 blend doesn't have any lube.  Castor doesn't mix well with NM, and with 50%NM, 35% meth and 15% castor you can expect mixing problems, especially in cool weather.

You can blend in ~10% nitrobenzene which will dissolve the castor and/or use some synthetic oil in place of some of the castor, but 50% with a big model engine is asking for problems.  NB is also quite poisonous, unlike NM.

What material did you make the crank and rod from?  

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein  

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